#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main(void) {
    int i, n;
    scanf("%d", &n);
    double sum = 0;
    for (i = 1; i <= n; i++) {
        sum += 1.0 / i;
    }
    printf("sum = %.6f", sum);
    return 0;
}